Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 201126
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
726 AM EDT SUN JUL 20 2014

.UPDATE...
ISSUED AT 659 AM EDT SUN JUL 20 2014

HAVE MADE ADJUSTMENTS BASED ON EARLY MORNING CONDITIONS...PRIMARILY
AFFECTING POPS. SHOWERS HAVE INCREASED IN COVERAGE OVER THE LAST FEW
HOURS...AND HAVE DROPPED MORE THAN A QUARTER INCH IN SOME LOCATIONS.
HAVE RAISED POPS FOR OUR EASTERN COUNTIES.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 311 AM EDT SUN JUL 20 2014

THE MID/UPPER LEVEL WAVE WHICH BROUGHT RAIN ON SATURDAY DEPARTED TO
THE NORTHEAST. HOWEVER...WE WERE LEFT WITH A MOIST ATMOSPHERE IN THE
LOW/MID LEVELS UNDERLYING A WEAK RESIDUAL MID/UPPER LEVEL TROUGH.
ISOLATED SHOWERS AND AREA OF DRIZZLE LINGERED EARLY THIS MORNING IN
THIS ENVIRONMENT.

THE MID/UPPER LEVEL TROUGH WILL CONTINUE TO WEAKEN THROUGH MONDAY...
WITH GEOPOTENTIAL HEIGHTS RISING AND TEMPS ALOFT SLOWLY WARMING. MID
LEVELS WILL GRADUALLY DRY OUT. THIS WILL RESULT IN SIGNIFICANT
WARMING AS PARTIAL SUNSHINE RETURNS. ANY PRECIP SHOULD BECOME LARGELY
DIURNAL IN NATURE. A WARM LAYER AT 650-700 MB WILL TRY TO KEEP DEEP
CONVECTION CAPPED. WILL NOT RULE OUT THE POSSIBILITY OF THE CAP BEING
BROKEN...BUT WITH WEATHER FEATURES BEING VERY WEAK AND WINDS ALOFT
LIGHT...ANY CONVECTION SHOULD REMAIN POORLY ORGANIZED. WITH THESE
CONSIDERATIONS...THE POP IS LIMITED TO NO MORE THAN 20-30 PERCENT.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 329 AM EDT SUN JUL 20 2014

THE UPPER LEVEL PATTERN FOR THE EXTENDED LOOKS TO BE TAKING AN
OVERALL GRADUAL AMPLIFICATION AS TIME GOES ON. THE UPPER LEVEL RIDGE
REMAINS OVER THE WEST THROUGH THE PERIOD WITH AN OVERALL DEEPENING
OF THE TROUGH OVER THE EASTERN CONUS. THIS TROUGH OVER THE EAST DOES
FILL A BIT AS THE RIDGE OVER THE SOUTHEAST REMAINS THROUGH THE EARLY
PORTION OF THE EXTENDED BEFORE SHIFTING EAST INTO THE ATLANTIC. AN
OVERALL DEEPENING OF THE EASTERN TROUGH TOWARDS THE END OF THE
EXTENDED ENSUES. THE AFOREMENTIONED FILLING OF THE TROUGH IN THE
MONDAY NIGHT PERIOD RESULTS IN A PIECE OF ENERGY BEING CUT OFF FROM
THE MAIN FLOW BY THE HEIGHT CENTERS OVER THE WEST AND
SOUTHEAST...LEAVING A CUT OFF CLOSED LOW ALONG THE LA AND MS GULF
COAST. THIS DISTURBANCE WILL BE A FOCAL POINT FOR PRECIP THROUGH THE
BEGINNING OF THE EXTENDED. FEATURING A COUPLE STRONG WAVES THROUGH
THE REST OF THE EXTENDED...THE SHORTWAVE MOVING THROUGH ON WEDNESDAY
INTO THURSDAY STILL LOOKS TO BE ON TRACK. HOWEVER...WHILE THE MODELS
DO SHOW SOME AGREEMENT...PARTICULARLY THE EURO HAS BEEN A BIT
INCONSISTENT WITH THIS WAVE AS IT IS QUITE A BIT WEAKER THAN THE
PREVIOUS RUNS BUT WILL STILL BE ABLE DIG FAR ENOUGH SOUTH TO KICK
THE AFOREMENTIONED DISTURBANCE OUT TO SEA. HEADING INTO THE
WEEKEND...A STRONG CLOSED LOW DROPS OUT OF THE NORTHWEST AND INTO
THE GREAT LAKES AND UPPER MS RIVER VALLEY REGION. THIS LOOKS TO
IMPACT THE OH VALLEY TOWARDS THE END OF THE EXTENDED AND JUST
BEYOND. MODEL TRENDS LATELY HAVE BEEN SHOWING THESE POTENT
SHORTWAVES IN THE FLOW AND THEN GRADUALLY WEAKENING THEM RUN TO
RUN...WILL BE INTERESTING IF THE MODELS FOLLOW SUIT WITH THIS
FEATURE.

FOR SOME SPECIFICS...THE SOUTHERLY WARM AND MOIST FLOW THROUGH MUCH
OF THE FIRST PART OF THE EXTENDED LOOKS TO STILL BE ON TRACK AND
WITH THE PINCHED OFF LOW OVER THE GULF STATES...THE CHANCE FOR
PRECIP WILL BE ON TAP EVERY AFTERNOON WITH AN INCREASE IN
INSTABILITY THROUGH WEDNESDAY. THE FRONT STILL POISED TO MOVE
THROUGH ON WEDNESDAY NIGHT INTO THURSDAY AND WILL PROVIDE A GOOD
CHANCE OF PRECIP. SO STAYED WITH THE HIGH POPS INHERITED FROM THE
MODEL ALL BLEND ON WEDNESDAY AND THURSDAY. THE TREND OF THE MODELS
WITH THESE FEATURES MOVING IN FROM THE NORTHWEST MAKES IT DIFFICULT
TO GET INTO ANY SPECIFICS WITH SEVERE WEATHER...ESPECIALLY THE
STRONG LOW DROPPING OUT OF THE NORTHWEST NEXT WEEKEND. WITH THIS IN
MIND...KEPT A DIURNAL TREND TO THE POPS THROUGH THE BEGINNING OF THE
EXTENDED WITH INCREASED CHANCES ON WEDNESDAY AND THURSDAY WITH THE
FRONT. FRIDAY LOOKS TO BE A QUITE COOL AND DRY DAY AFTER FRONTAL
PASSAGE WITH LITTLE CHANCE OF PRECIP. THE MENTIONED STRONG LOW LIES
JUST OUTSIDE THE 7 DAY WINDOW BUT BEARS SOME WATCHING. THE COOLER
AIR MASS SET TO MOVE IN BEHIND THE FRONT WILL BE ENOUGH TO DROP MAX
TEMPS 5 TO 7 DEGREES BELOW NORMAL VALUES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 726 AM EDT SUN JUL 20 2014

CONDITIONS WERE LARGELY MVFR EARLY THIS MORNING...WITH SOME POCKETS
OF IFR AND VFR. THERE WERE ALSO SHOWERS AFFECTING MANY LOCATIONS. THE
SHOWERS SHOULD SHOW AN OVERALL DIMINISHING TREND DURING THE LATE
MORNING AND EARLY AFTERNOON...WITH CEILINGS THEN BREAKING UP DURING
THE AFTERNOON TO ALLOW A RETURN OF VFR. SOME REDEVELOPMENT OF
SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE AS HEATING TAKES PLACE THIS
AFTERNOON...BUT THE PROBABILITY IS TOO LOW AT ANY GIVEN LOCATION TO
WARRANT INCLUSION IN TAFS. EXTENSIVE FOG DEVELOPMENT IS EXPECTED LATE
TONIGHT...WITH WIDESPREAD IFR BY DAWN ON MONDAY.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...HAL
SHORT TERM...HAL
LONG TERM...SHALLENBERGER
AVIATION...HAL





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